I know the budget for PFO is likely to be somewhat limited, but please don't skimp on the sound effects and music.
When done correctly, sound/music can add just as much (if not more) than decent graphics.
If you're doubting the power of background music, just check out some of the WoW background music clips on Youtube. Scroll down to the comments and behold the intense feelings of nostalgia that they create.
http://youtu.be/Pw3H92vRBfA
http://youtu.be/BLf5h25107k
